(D)VCS for $HOME mirroring
Many people use a Version Control Systems to mirror their $HOMEs in several networked computers. This has clear advantages of doing incremental backups of your $HOME (TimeMachine, anyone? 
) and keeping it in sync across several computers. In the past, I’ve used Mercurial to do this job, but some months ago I switched to Subversion because I wanted to use try the one-VCS-for-all meme (Subversion is now being used by FreeBSD in case you don’t know). Unfortunately, it didn’t work out well. The computer where I kept the svn repo had a horrible hard disk failure and this made me wonder if I was using the right tool. Today, I switched back to Mercurial and I guess this is the right tool for the job.